Several types of prior art water systems have been proposed for heating and/or cooling a plurality of rooms in a building. In the basic water system, heat exchange units are provided in the various rooms and are connected with a main closed circuit which includes either hot water heating apparatus or water cooling apparatus or both. The heating or cooling apparatus raises or reduces the temperature of the water and a suitable pump forces the water into the main flow circuit and into the heat exchange units, after which it is returned to the apparatus for either heating or cooling.
A majority of these prior art systems usually require several horizontally extended conduits to connect each heat exchanger to the main flow circuit which adds to the materials costs of the system. Also, the labor required to make the necessary connections is an additional expense.
In the type of system in which two risers is used, the system must be manually converted from a heating mode to a cooling mode, or vice versa, at the appropriate time of the year. This requires the entire system to be shut down and the use of a skilled operator to effect the change, and, of course, makes it impossible for some of the individual units in the system to be used in one mode and other units used in the other mode at the same time.
Two previous U.S. Pat. Nos. (3,648,766 and 3,765,478) by the present applicant have successfully overcome the abovedescribed disadvantages through the use of a damper arrangement. Damper arrangements, like any other movable part, suffer from the disadvantage of possible mechanical failure, as well as increased production costs.